This application claims the benefit of U.S. application Ser. No. 60/006,729 express mailed Nov. 14, 1995, entitled PHASE-SEPARATED, NON-CRYSTALLINE OPAL GLASSES, by John L. Stempin and Dale R. Wexell.
The invention is directed to the production of spontaneous opal glasses which contain amorphous particles as the opacifying or light-diffusing phase. The glasses are phase separated, but non-crystalline, exhibit a very dense, milky-white appearance (unless colorants are added thereto), and strongly resist weathering and attack by acids and alkaline detergents, thereby recommending their utility for culinary ware and tableware.
This type of glass has been termed an immiscible opal, i.e., an opal glass wherein the opacifying phase is a glass which is insoluble in the basic glass matrix. Numerous attempts have been pursued in the past to develop an example of this type of opal glass which combines good chemical durability and resistance to weathering with a dense, white opacity.
Several attempts have been made in the past to develop opal glasses having the
above properties. Examples of such glasses are disclosed in U.S. Pat. Nos. 4,309,219 (herein incorporated by reference); 3,498,810; 3,506,464; 3,661,601; 3,723, 144; and 3,728,139.
There continues to be a need for opal glasses demonstrating dense opacity and good chemical durability and resistance to weathering, as well as good aesthetic appearance. Accordingly, the object of the present invention is to develop an improved opal glass, exhibiting excellent opacity and good chemical durability.